The core patterning step in the semiconductor substrate manufacturing process uses a wet etch process to remove metal from a masked substrate. The wet etch process begins with a layer of copper disposed on a typically non-conductive core material. A dry film resist layer is deposited on the copper layer. The desired pattern is masked on the dry film resist layer prior to curing the dry film resist layer. The dry film resist is developed to remove those portions of the dry film resist that were NOT masked prior to curing, exposing the copper layer in the areas where the dry film resist was removed. An etchant solution, applied under pressure selectively removes the exposed portions of the copper layer. The extent to which the copper layer is removed depends on a variety of factors including the etchant used, the pressure at which the etchant is applied, and the duration the etchant is applied, among others. After etching, the cured dry film resist is removed, exposing the underlying copper layer. Using traditional etching techniques, the removal of copper is essentially isotropic (i.e., equal in all directions radiating outward from the surface of the exposed copper layer). The isotropic nature of the etching process limits substrate component density achievable using current photolithographic techniques.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications and variations thereof will be apparent to those skilled in the art.